Just put a stop in each town that's willing to pay for it, and expect each ski area to provide buses from the mainline (or build their own gondola). You don't have to acquire any right-of-way, just a base for a tower every now and then.

Still Herebeen scared and battered. My hopes the wind done scattered. Snow has friz me, Sun has baked me,Looks like between 'em they done Tried to make meStop laughin', stop lovin', stop livin'-- But I don't care! I'm still here! Langston Hughes

If the gondola tops out at 65 kilometers/hr, that'd still be a longish ride, especially with multiple stops. Golden to Vail is almost 150 kilometers, so 2.5 hours plus stops.On the other hand, the driving time from Vail on crowded days is probably more than 3 hours each way, so it could help if some of the skiers would ride it (not a sure thing). Getting by the tunnels would be an issue, although they could just go over. Interesting suggestion, but I think free buses would be cheaper, faster, higher capacity, and more comfortable.

Also, capacity would be limited by the boarding speed, maybe 3000 people per hour - not nearly enough, as I-70 in the carries about 30,000 vehicles per day (total both directions), representing over 50,000 people on peak days.